to gas hydrates and assigned most of the thermal effects to the dominant presence of water in the hydrate.
1883
de Forcrand observed that a number of double hydrates had well‐defined cubic, cubo‐octahedral, or truncated octahedral morphologies which were not acted on by polarized light.
1884–1885
Bakhuis Roozeboom provided hydration numbers for SO2, Cl2, and Br2 hydrates and his phase equilibrium diagrams clearly showed the pressure–temperature fields of hydrate stability. Cailletet, Wróblewski, and Bakhuis Roozeboom observed a memory effect that increased the reformation rate of hydrate from solutions of decomposed hydrate.
1884
Le Châtelier used the Clausius–Clapeyron equation for the variation of vapor pressure of the hydrates with temperature and was the first to use the equation to determine gas hydrate compositions.
1885
Chancel and Parmentier reported a simple hydrate of chloroform. This was one of the first so‐called “liquid hydrates” whose guest components are liquids at ambient temperature.
1887–1888
Bakhuis Roozeboom applied the Gibbs phase rule to heterogeneous equilibria and systematically classified chemical and physical processes according to number and nature of the components and phases present. He published on the treatment of the invariant points at which equilibrium lines meet.
1888
Villard prepared hydrates of CH4, C2H6, C2H4, N2O, and propane (1890).
1890
Villard recognized the stabilizing effect of air on the decomposition of gas hydrates. In the search for other “help‐gases” he identified both hydrogen at 23 atm and oxygen at 2.5 atm as increasing the decomposition temperature of ethyl chloride.
1897
On the basis of careful measurements on the large number of hydrates then available, Villard presented a definition of the composition of gas hydrates (Villard's law).
1897
de Forcrand and Thomas discovered new help‐gases (CO2, C2H4, C2H2, and SO2).
1902
de Forcrand used calorimetric data and a generalization of Trouton's rule to calculate hydrate compositions for 15 hydrates. About half had compositions in agreement with Villard's law.
1923
Bouzat produced summary statements giving the then current definition of hydrates, their structure, and composition.
1926
Schroeder wrote an influential monograph summarizing the state of knowledge of gas hydrate to that date.
1934
Hammerschmidt, after reading Schroeder's book, showed that gas hydrates are more likely to form plugs in natural gas pipelines than ice.
1936–1937
Nikitin prepared mixed hydrates of noble gases and SO2 and showed that the noble gases could be separated by partitioning between the solid hydrate and the gas. His observations were first consistent with the “solid solution” nature of hydrates.
1946
Deaton and Frost presented experimental data on hydrate phase equilibria of natural gas components and methods of hydrate prevention.
1946
Miller and Strong proposed natural gas storage in hydrate form.
1947
Powell coined the term “clathrate” for materials having a guest molecule residing in a cavity formed in a host lattice.
1949
von Stackelberg used X‐ray diffraction data to propose a structure for a gas hydrate of chloroform and H2S. Although the structure, based on a lattice with holes for guests, was incorrect, it was a radical departure from the molecular structure current up until that time. von Stackelberg had studied the X‐ray diffraction of gas hydrates prior to this time, but his original photographic plates had been destroyed in aerial bombardment during World War II.
1951
Clausen introduced the pentagonal dodecahedron as a structural component of gas hydrates, and von Stackelberg and Muller's X‐ray diffraction data confirmed the crystal structure of the “structure II” (sII or CS‐II) hydrate proposed by Clausen.
1952
Clausen, von Stackelberg, and Pauling and Marsh provided a structure for “structure I” (sI or CS‐I) gas hydrates.
1952
Delsemme and Swings suggested the presence of gas hydrates in comets and interstellar grains. Delsemme later suggested that the outgassing of comets on approaching the sun could be due to decomposition of hydrates.
1957–1967
Barrer and coworkers studied hydrate thermodynamics, kinetics, and separation of gas mixtures with hydrate formation.
1959–1970
Jeffrey and coworkers used single‐crystal X‐ray diffraction to obtain structural data for clathrate hydrates, semi‐clathrates, and salt hydrates.
1959
van der Waals and Platteeuw presented the “solid solution” statistical thermodynamics model for clathrate hydrates.
1961
Miller and Pauling hypothesized hydrate formation as a mechanism for anesthesia arising from inert noble gases, in particular xenon.
1961
Miller suggested the presence of gas hydrates in the planets, planetary rings, and interstellar space in the solar system.
1963
Davidson used dielectric methods to study clathrate hydrates. He discovered new water‐soluble (polar) guests for clathrate hydrates, measured the dynamics of guest and host molecules, found that water molecule reorientation rates depend on the nature of the guest molecule, and postulated the presence of guest–host hydrogen bonding capable of generating Bjerrum defects.
1965
Makogon reported on natural gas hydrates found in the Siberian permafrost.
1965
Kobayashi and coworkers applied the Kihara intermolecular potential to van der Waals–Platteeuw theory to represent the guest–cage interactions.
1965
Davidson and coworkers started nuclear magnetic resonance (NMR) measurements on clathrate hydrates and demonstrated that the SF6 guest in sII clathrate rotates isotropically even at 77 K.
1966
Glew and Rath showed that the equilibrium compositions of Cl2 and EO clathrate hydrates are variable, in accordance with van der Waals–Platteeuw theory.
1968
Glew and Haggett studied EO hydrate growth kinetics and showed that the process is governed by heat transfer over a wide range of concentrations.
to gas hydrates and assigned most of the thermal effects to the dominant presence of water in the hydrate.
